An earthquake’s intensity is determined by observing its effects at a particular place on the Earth’s surface. Intensity depends on the earthquake’s magnitude, the distance from the epicenter, and local geology. These scales are based on reports of people awakening, felt movements, sounds, and visible effects on structures and landscapes. The most commonly used scale in the United States is the Modified Mercalli Intensity Scale, and its values are usually reported in Roman numerals to distinguish them from magnitudes.

Past damage in New Jersey

New Jersey doesn’t get many earthquakes, but it does get some. Fortunately most are small. A few New Jersey earthquakes, as well as a few originating outside the state, have produced enough damage to warrant the concern of planners and emergency managers.

Damage in New Jersey from earthquakes has been minor: items knocked off shelves, cracked plaster and masonry, and fallen chimneys. Perhaps because no one was standing under a chimney when it fell, there are no recorded earthquake–related deaths in New Jersey. We will probably not be so fortunate in the future.

More recently, in the 1970’s and early 1980’s, earthquake risk along the Ramapo Fault received attention because of its proximity to the Indian Point, New York, Nuclear Power Generating Station. East of the Rocky Mountains (including New Jersey), earthquakes do not break the ground surface. Their focuses lie at least a few miles below the Earth’s surface, and their locations are determined by interpreting seismographic records. Geologic fault lines seen on the surface today are evidence of ancient events. The presence or absence of mapped faults (fault lines) does not denote either a seismic hazard or the lack of one, and earthquakes can occur anywhere in New Jersey.

Frequency of Damaging Earthquakes in New Jersey

Records for the New York City area, which have been kept for 300 years, provide good information

for estimating the frequency of earthquakes in New Jersey.

Earthquakes with a maximum intensity of VII (see table DamagingEarthquakes Felt in New Jersey )have occurred in the New York City area in 1737, 1783, and 1884. One intensity VI, four intensity V’s, and at least three intensity III shocks have also occurred in the New York area over the last 300 years.

The 1995 earthquake in Kobe, Japan, is an example of what might happen in New Jersey in a similar quake. It registered a magnitude 7.2 on the Richter scale and produced widespread destruction. But it was the age of construction, soil and foundation condition, proximity to the fault, and type of structure that were the major determining factors in the performance of each building. Newer structures, built to the latest construction standards, appeared to perform relatively well, generally ensuring the life safety of occupants.

Structures have collapsed in New Jersey without earthquakes; an earthquake would trigger many more. Building and housing codes need to be updated and strictly enforced to properly prepare for inevitable future earthquakes.

Share this:

Like this:

Related

Published by andrewtheprophet

This is The Prophecy. The Prophecy is much more than seeing into the future. For The Prophecy sees without the limits of time. For The Prophecy sees what is, what was, and what always shall be.
View all posts by andrewtheprophet